Duct board with low weight water repellant mat

ABSTRACT

A duct board or duct liner product is provided comprising an insulating layer formed from fibrous material bound with a resin binder; an outer facing layer adhered to an outer surface of the insulating layer; and a water repellant mat facing adhered to an interior surface of the insulating layer opposite the outer surface to form a duct board material, the mat facing having a weight of less than 1.1 lb/100 ft 2  (53.6 g/m 2 ) and having at least an INDA 2 water repellence rating using the IST 80.6-92 water repellency test method.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 10/342,849, entitled “Duct Board With Water Repellant Mat”filed Jan. 14, 2003, the entirety of which is hereby incorporated byreference herein in its entirety.

This application is related to U.S. patent application Ser. No.10/141,595, entitled “Duct Board Having Two Facings” filed May 8, 2002,the entirety of which is hereby incorporated by reference herein in itsentirety.

FIELD OF THE INVENTION

The present invention relates to building products in general and, inparticular, to duct board and duct liner materials and ducts madetherefrom.

BACKGROUND

Ducts and conduits are used to convey air in building heating,ventilation and air conditioning (HVAC) systems. In many applications,especially in commercial and industrial construction, the ducts arelined with flexible thermal and sound insulating material. The liningenhances the thermal efficiency of the duct work and reduces noiseassociated with movement of air therethrough. Duct liner may compriseany suitable organic material or inorganic material, e.g., mineralfibers such as fiber glass insulation or the like. Typical fiber glassduct liners, for example, are constructed as fiber glass mats havingdensities of about 1.5 to 3 pounds per cubic foot (pcf) and thicknessesof about 0.5 to 2 inches. To prevent fiber erosion due to air flow, theinsulation may include a coating of on its inner or “air stream”surface. The air stream surface of the insulation is the surface thatconveys air through the duct and is opposite the surface that contactsthe duct sheet metal in the final duct assembly. The coating also servesto protect the insulation during brush and/or vacuum cleaning of theinterior of the duct. Examples of duct liners having coatings on theirinner surfaces are provided in U.S. Pat. Nos. 3,861,425 and 4,101,700.Several coated insulation duct liners or boards are marketed under thetrade designations Toughgard® and Ultra*Duct™ Gold by CertainTeed Corp.of Valley Forge, Pa., Aeroflex® and Aeromat® by Owens Corning FiberglasCorp. of Toledo, Ohio, Permacote®, Polycoustic™ by Johns Manville Corp.of Denver, Colo. and Knauf Airduct Board-M by Knauf Insulation ofShellbyville, Id.

Other insulated HVAC systems use ducts either fabricated from or linedwith rigid duct boards or tubes. Duct boards are rigid members formedfrom resin-bonded mineral fibers and whose air stream surfaces may alsobe provided with protective coatings. Duct boards typically havedensities of about 3 to 6 pounds per cubic foot (pcf) and thicknesses ofbetween about 0.5 to 2 inches. Coated and uncoated duct boards aremarketed under a variety of trade designations from the aforementionedmanufacturers of duct liners. Whether provided on duct liners or ductboards, dedicated water-resistant coatings add to the cost andcomplexity of manufacturing these products.

It is well known that microorganisms will grow in an environment wheremoisture and nutrients are present and that many species ofmicroorganisms have a negative impact on indoor air quality (IAQ). Ifliquid water leaks into air duct insulation, the water may collect andstagnate in the insulation and support the growth of microorganisms.

To address the problem of microorganism growth in HVAC systems, U.S.Pat. Nos. 5,314,719; 5,379,806; 5,487,412 and 5,783,268 discloseproviding antimicrobial agents on or in the air-conveying surfaces ofimpermeable duct liners and/or duct boards. However, these antimicrobialagents have very limited zones of effectiveness. That is, they tend toprevent microbe formation only in their immediate vicinity. U.S. Pat.No. 5,314,719, for example, describes a zone of antifungal inhibition ofabout one millimeter. Typical duct liners and duct boards haveinsulation thicknesses ranging from about one-half to two inches. Inthese products, such a limited zone of inhibition would be essentiallyuseless in preventing microorganism formation caused by duct insulationthat becomes saturated by water entering through the exterior walls andseams of the duct.

Moisture impermeable coatings, if applied to the airstream surface ofair duct insulation products, inhibit ingress of water into theinsulation and attendant microorganism formation therein. U.S. Pat. No.3,861,425 discusses providing HVAC ducts either composed of or linedwith fibrous glass insulation media such as batts, mats, boards or thelike with such coatings. While certain coatings may provide the benefitsof fiber erosion protection and moisture resistance, they add to thecost and complexity of the products and their methods of manufacture.Coatings applied to the air stream surface of fibrous insulationproducts are applied to those products after their formation. Thisrequires application of the coating to the previously formed insulationproduct by brush, roller, sprayer or by some other means or method andthereafter allowing the coating to cure or dry. This post-formationcoating step may prolong the time required to manufacture the insulationproduct and, whether performed manually or automatically, must becarefully monitored in order to assure uniformity in application of thecoating.

As an alternative to coated duct liners and duct boards, at leastCertainTeed Corp. and Knauf Fiber Glass GmbH offer duct liners or ductboards having glass fiber insulation covered with a layer of non-wovenfacing material which defines the air stream surface of those products.The facing material produces a durable surface that protects the airduct from fiber erosion.

However, both uncoated fibrous insulation HVAC duct products and someproducts that are covered with facing material possess limited inherentmoisture resistance. Consequently, they are susceptible to microorganismformation in the event they become wet.

Further, the coating selected for these coated duct liners and ductboards can significantly add to the products cost.

SUMMARY OF THE INVENTION

A duct board or duct liner product and method of making the same isprovided. The duct board or duct liner product comprises an insulatinglayer formed from fibrous material bound with a resin binder; an outerfacing layer adhered to an outer surface of the insulating layer; and awater repellant mat facing adhered to an interior surface of theinsulating layer opposite the outer surface to form a duct boardmaterial, the mat facing having a weight of less than 1.1 lb/100 ft²(53.6 g/m²) and having at least an INDA 2 water repellence rating usingthe IST 80.6-92 water repellency test method.

By limiting the weight of the nonwoven facing, significant cost savingscan be realized while providing a cost effective, abuse resistant waterrepellant airstream surface for the mineral fiber duct product.Additional cost savings can be realized in embodiments where noadditional water repellent is added to the binder of the duct board oradhesive used to adhere the nonwoven to the duct board.

In one embodiment, the mat facing has a water repellent materialintegral therein and the mat facing has a weight of between about 0.80lb/100 ft² (39.0 g/m²) and 0.91 lb/100 ft² (44.2 g/m²). The mat isadhered to a surface of said insulating layer by an adhesive, and theadhesive and insulating layer are substantially free of water repellentadditives or agents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a duct board material according toone embodiment.

FIG. 2 is a diagram of apparatus for forming the insulation layer of thematerial shown in FIG. 1.

FIG. 3 is a diagram of apparatus for applying the mat facing to the ductboard material shown in FIG. 1.

FIG. 4 is an isometric view of the duct board of FIG. 1, after it isfolded into an air duct.

DETAILED DESCRIPTION

Application Ser. No. 09/789,063, filed Feb. 20, 2001, and applicationSer. No. 09/788,760, filed Feb. 20, 2001 are incorporated by referenceherein in their entireties.

This description of the exemplary embodiments is intended to be read inconnection with the accompanying drawings, which are to be consideredpart of the entire written description. In the description, relativeterms such as “lower,” “upper,” “horizontal,” “vertical,”, “above,”“below,” “up,” “down,” “top” and “bottom” as well as derivative thereof(e.g., “horizontally,” “downwardly,” “upwardly,”etc.) should beconstrued to refer to the orientation as then described or as shown inthe drawing under discussion. These relative terms are for convenienceof description and do not require that the apparatus be constructed oroperated in a particular orientation. Terms concerning attachments,coupling and the like, such as “connected” and “interconnected,” referto a relationship wherein structures are secured or attached to oneanother either directly or indirectly through intervening structures, aswell as both movable or rigid attachments or relationships, unlessexpressly described otherwise.

FIG. 1 is a cutaway view of a portion of a duct board or duct linermaterial 10. A duct board or duct liner 10 comprises an insulating layer12, 13 formed from fibrous material bound with a resin binder, an outerfacing layer 18 adhered to an outer surface of the outer insulatinglayer portion 13 and a water repellant mat facing 14 adhered to aninterior surface of the inner insulating layer portion 12 opposite theouter facing layer 18 to form a duct board or duct liner material. Themat facing 14 provides sufficient water repellency to repel a mixture ofabout 40% isopropanol and about 60% water under IST Test No 80.6-92. Themat facing 14 may optionally provide sufficient water repellency torepel a mixture of greater than 40% isopropanol. The duct board or ductliner material 10 is formed into a tubular shape capable of conductingair, with the mat facing 14 on an interior thereof. FIG. 4 shows anexemplary air duct formed from the duct board 10. A duct liner wouldhave a similar appearance, but would have a lower density suitable forplacement inside a duct. Although a rectangular duct is shown the ductmay be formed into a non-rectangular tubular shape, such as round oroval, as is known in the art.

The mat facing 14 may be formed from a woven or non-woven fibermaterial. The material may be inherently water repellant, or it may betreated with a water repellant material that includes a treatment suchas wax-asphalt emulsion, silicone or fluorocarbon, for example, toprovide the desired water repellency.

A preferred mat material 14 has a water repellency sufficient to repel adrop including at least 80% isopropyl alcohol and water for a minimum offive minutes, using an IST 80.6-92 test method. Materials that repel upto 100% isopropyl alcohol in an IST 80.6-92 test may be used. In somepreferred embodiments, the mat 14 is formed from water repellant 40#Manniglass 1886 Black mat or 1786 Black mat from Lydall Inc. of GreenIsland, N.Y. or water repellant Elasti-Glass® 3220B mat from JohnsManville of Denver, Colo.

In other embodiments, the mat 14 is formed from filament glass fibers inan acrylic-based binder, such as Johns Manville Dura-Glass® 8440 with awater repellant (e.g., silicone or fluorocarbon) applied thereto.

Other mat materials providing similar or better degrees of waterrepellency may alternatively be used. For example, such materials mayinclude non-woven mats of glass fibers randomly dispersed into a web ina wet-laid process, bound in an acrylic or other resin system, and posttreated with a fluorocarbon based coating that provides the desireddegree of water repellency.

Product 10 comprises an insulating layer 12, 13 of mineral fibers suchas glass fibers, refractory fibers or mineral wool fibers bonded by asuitable resin and mat facing 14 of adhered thereto by adhesive 16,wherein the facing material 14 defines the air stream surface for theboard or tube. Binders that may be used to bind the fibers of insulatinglayer 12, 13 may include, without limitation, the phenolic bindersdisclosed in U.S. Pat. Nos. 5,300,562 and 5,473,012, the disclosure ofwhich are incorporated herein by reference. Product 10 may have adensity of about 0.5 to 6 pounds per cubic foot (pcf) and a thickness ofbetween about 1.27 to 5.08 centimeters (0.5 to 2 inches). The thicknessand density of insulation layer 12, 13 is dictated by whether theproduct is a duct board or duct liner, and is also influenced by thelevels of acoustic and/or thermal insulation that are desired ornecessary for a particular building installation. One of ordinary skillin the art understands that other known duct board fabrication processesmay be used.

Although the piece of duct board material shown in FIG. 1 has a femaleshiplap edge and a male shiplap edge with a strip of the outer facinglayer 18 overhanging the male shiplap edge, other configurations areformed with or without shiplap edges.

In some embodiments, the water repellant mat facing 14 alone providesthe desired degree of water repellency. In other embodiments, asdescribed below, the water repellency of the product 10 is enhanced byan additive in either the binder of the insulation layer 12, 13, theadhesive joining the facing 14 to the insulation 12, or both.

As will be appreciated by reference to FIG. 1, the insulation layer 12,13 is formed as a series of accumulated layers of resin-bonded fiberswhich, in the end product, may be intertwined and appear and exist as acontinuous homogeneous mass rather than as a plurality of distinct ordiscrete strata or lamina. For simplicity of illustration andexplanation, product 10 is referred to below as comprising first andsecond portions 12 and 13, although typical rigid duct boards and tubesinclude many bound layers. The location of the dashed line betweenportions 12 and 13 is optional. In some embodiments, portions 12 and 13are continuous and of identical composition, and may be considered asingle layer. In other embodiments, as described below, portion 12 hasan additive not contained in portion 13, portion 13 has an additive notcontained in portion 12, or portion 12 and 13 contain differentadditives. In some embodiments, portion 12 is thicker. In otherembodiments, portion 13 is thicker.

In some embodiments, the water repellency of the duct board or tube isoptionally enhanced by incorporating a hydrophobic agent into the binderof at least one of the portions 12, 13. In one example, the hydrophobicagent is incorporated into portion 12 which is closer to the air streamsurface of product 10, and adjacent to the facing 14; portion 13 doesnot, therefore, have to have the hydrophobic agent in the binderthereof, but may. In this way, liquid water or other aqueous liquidsfrom the interior of the duct which penetrates facing 14 is furtherrepelled from entering product 10, thereby reducing the likelihood ofmicrobial growth in the insulation. Preferably, a foil/scrim/paperlaminate or other suitable vapor retarder layer 18 is adhered orotherwise affixed to the face of product opposite the air stream surfaceof layer 12 to prevent moisture from entering the insulation from theambient environment.

FIG. 2 shows a forming section for forming the insulating layer 12, 13which includes the optional hydrophobic agent in the binder of portion12. Insulation layers 12 and 13 may be made in forming section 19 bymelt spinning molten material, such as glass, into veils 20 of finefibers using a plurality of fiberizing units 22 a-22 f. The veils offibers enter a forming hood 24 where a binder, such as a phenolic resin,in an aqueous carrier (or water and binder in sequence) is sprayed ontothe veils 20. In the forming hood 24, fibers are accumulated andcollected as a web on a chain, belt or other conventionally-drivenconveyor 26. In order to impart hydrophobicity to portion 12, at leastfiberizing unit 22 f is configured to dispense binder having ahydrophobic agent incorporated therein. After the web exits the formingsection 19, it is conveyed to an unillustrated conventional curing ovenfor compressing and curing the web to a desired thickness and density.

While in the oven, portions 12, 13 are simultaneously heated in order tocure the binder and adhere the portions to one another so as to form thehomogeneous mass of product 10. Preferably, the multiplicity of layersof fibers are held together by unillustrated heated platens or the likeunder sufficient pressure to compress the mass of fibers in portions 12and 13 against each other. After product 10 exits the curing oven, vaporretarder layer 18 is applied to the surface of layer 13 opposite the airsteam surface.

In some embodiments, the binder used in at least portion 12 includes atleast one hydrophobic agent such as silicone, oil, fluorocarbon, waxes,wax-asphalt emulsions, acrylics, other emulsions, latexes, polyvinylacetates, etc. or the like in an effective amount sufficient to renderthe product water repellent and resistant to aqueous solutionscontaining moderate quantities of solvent regardless of the waterrepellency of the airstream facing layer 14. Depending upon thehydrophobic agent selected, effective amounts of hydrophobic agent mayrange in a ratio of about 1:200 to 1:5 hydrophobic agent to binder. Inone embodiment, a commercially available hydrophobic agent suitable forthese purposes is DC 347 silicone emulsion manufactured by Dow ComingCorporation of Midland, Mich. Good water repellency characteristics havebeen shown when this agent is present in a ratio of about 1:24 relativeto phenolic resin binder. Alternative hydrophobic agents suitable foruse with phenolic resin include Mulrex®, an oil emulsion marketed by theMobil Oil Corporation of Fairfax, Va. and stock number SL 849 oilmarketed by Borden Chemical, Inc. of Columbus, Ohio. Good waterrepellency characteristics have been shown when Borden® SL 849 oil ispresent in a ratio of about 1:16 relative to phenolic resin binder.

Although an example is described above in which one portion 12 of theinsulating layer includes a hydrophobic agent in the binder thereof, andanother portion 13 of the insulating layer may not include a hydrophobicagent in the binder thereof, other embodiments include the hydrophobicagent in the binder of the entire insulating layer 12, 13. As notedabove, if the mat facing 14 provides the desired water repellence (aloneor in combination with a water repellant adhesive 16), then neitherportion 12 or 13 requires a hydrophobic agent.

An exemplary rotary process described above is advantageous for making aduct board product. In the case of duct liner product, a similar flameattenuated process is used. Alternatively, a duct liner product can befabricated using a textile mat forming process, in which textile fibersin continuous strands are chopped into 2 to 5 inch lengths and formedinto a mat or board by an air-laid process. A hydrophobic agent such asa silicone, fluorocarbon or wax may be added to the powdered binder usedin this process.

In some embodiments, the water repellency of the duct board or tube 10is enhanced by incorporating a hydrophobic agent into adhesive 16. Inthis way, liquid water or other aqueous liquids in the interior of theduct which penetrate facing 14 are repelled from entering the interiorportion 12 of the insulation layer 12, 13 thereby further reducing thelikelihood of microbial growth in the insulation.

Referring to FIG. 3, insulation layer 12, 13 may be made in a formingstation 19 as described above, by melt spinning molten material, such asglass, into fine fibers, and spraying a binder, such as a phenolic resinbinder in an aqueous carrier, onto the fibers, and collecting the fibersas a web on a conveyor. The web is then passed through a conventionalcuring oven 30 or other means for curing and compressing the web to adesired thickness after the web exits the forming station. Note thatportion 13 is not shown in FIG. 3. For purpose of this example, it isoptional, but not necessary, to have distinguishable portions 12, 13 inthe insulating layer.

In some embodiments, a continuous web of facing layer 14 is dispensedfrom a roll 32 and is applied to one surface of insulation layer 12prior to curing of the binder in the insulation. Prior to adhering thefacing layer 14 to the insulation layer 12, an adhesive 16 is applied toeither or both of the facing layer 14 and the insulation layer 12.Adhesive 16 may be continuously applied to the underside of facing layer14 via an applicator roll 34 rotatably supported in a pan 36 or similarreceptacle which contains adhesive appropriate for securely adheringlayers 12,14 to one another following curing. It will be understood thatadhesive 16 may be applied to either or both of layers 12, 14 by othermeans such as spraying or brushing.

In applying adhesive, care should be taken to minimize the amount ofadhesive 16 that penetrates through the facing all the way through tothe (inner) airstream surface of facing 14 and becomes deposited on thatsurface. Adhesive 16 on the inner surface of mat 14 may present a morewettable surface than the bare facing 14. Thus, if the airstream surfaceis partially or totally coated with adhesive 16, this may increase thesurface tension of the surface and reduce water repellence below that ofbare facing 14.

Although not limited thereto, a preferred adhesive is a phenolic resinhaving generally the same or similar composition as the binder that isused to bind the fibers in insulation layer 12. However, phenolic resinadhesives have limited hydrophobicity.

Accordingly, the adhesive used to attach facing 14 to insulation layer12 may optionally include at least one hydrophobic agent such assilicone, oil, fluorocarbon, waxes or the like in an effective amountsufficient to render the product essentially impermeable to water andresistant to aqueous solutions containing moderate quantities ofsolvent, regardless of the water repellency of the facing 14. Effectiveamounts of hydrophobic agent may range in a ratio of about 1:20 to1:200, and more preferably about 1:40, hydrophobic agent to binder. Acommercially available hydrophobic agent suitable for these purposes isDC 347 silicone emulsion manufactured by Dow Corning Corporation ofMidland, Mich.

The layers 12, 14 may travel at any desired synchronous speed and theapplicator roll 24 may be rotated at any speed sufficient to thoroughlyapply the adhesive 16 to the underside of the moving facing layer web14. Acceptable results have been demonstrated at a moving layer speedsof about 80 feet per minute coupled with applicator roll 24 rotationspeeds of about 3-20 rpm. A placement means 38 such as an idler rolleror the like may be used to facilitate placement of the layer 14 on layer12. Product 10 is then passed by an unillustrated conveyor to a curingoven 30. While in the oven, layers 12,14 are simultaneously heated inorder to cure the binder and adhesive 16. Preferably, layers 12,14 areheld together by unillustrated heated platens or the like undersufficient pressure to compress the facing layer 14 against theinsulation layer 12. Heating the two layers under compression securelybonds the facing layer 14 to the thermal insulation layer 12. Vaporretarder layer 18 (shown in FIG. 1) may be applied to the surface ofinsulation layer 12 opposite facing layer 14 after the insulation boardexits the curing oven. After the curing oven, the rough edges of theboard may also be removed, such as with a circular saw. The duct boardis then cut to length and packaged.

EXAMPLE

Samples were constructed with facing 14 made of Johns Manville 3220B andLydall Manniglass 1886, on a fiber glass insulation board with aphenolic binder. The samples were constructed at different conveyor linespeeds of 80 and 92 feet per minute (which affects the density of theinsulating layer 12). In these samples, hydrophobic agents were notadded to the binder of insulating layer 12, or to the adhesive 16. Theresults of evaluating the boards' water repellency by placing drops ofwater and water/alcohol solutions on the surface of the board were asset forth in Table 1. Test results for a commercially available KnaufAir Duct Board-M with Hydroshield Technology EI475 duct board are alsoprovided for comparison. The term “OK” indicates that droplets did notpenetrate the surface in the referenced period of time. TABLE 1 JM 3220BJM 3220B Lydall 1886 Lydall 1886 Board @80 @92 @80 @92 Knauf Samplefeet/minute feet/minute feet/minute feet/minute Hydroshield Water(100%)OK > 1 hour OK > 1 hour OK > 1 hour OK > 1 hour OK 15 min 10% OK > 1hour OK > 1 hour OK > 1 hour OK > 1 hour OK 15 min Isopropanol 20% OK >1 hour OK > 1 hour OK > 1 hour OK > 1 hour OK 15 min Isopropanol 30%OK > 1 hour OK > 1 hour OK > 1 hour OK > 1 hour Soaked Isopropanolimmediately (<1 minute) 40% OK > 1 hour OK > 1 hour Some soaked OK > 15Soaked Isopropanol in <5 minutes minutes immediately (<1 minute) 50%OK > 1 hour OK > 1 hour Some soaked Some Soaked Soaked Isopropanol in <5minutes in <15 immediately minutes (<1 minute)

An extended test was conducted on the sample prepared using JM 3220Bwith a line speed of 80 feet/minute. The sample was placed under runningtap water for over seven hours, at an angle of approximately 60 degreesfrom the horizontal, and water dripped from a height of 13.3 centimeters(5.25 inches). After seven hours, there was no penetration of waterexcept for the bottom edge of the board, where water soaked in about 2.5centimeters (1 inch) from the edge (In the sample, the mat did not wraparound the bottom edge, so the bare insulation material was exposeddirectly to the running/dripping water stream). A cross section of theboard showed that the portion of the board directly under the drip ofwater appeared dry.

In an alternative embodiment, the duct board or duct liner productachieves at least an INDA 2 water repellence rating, meaning the producthas sufficient water repellency to repel a mixture of 20% isopropanoland about 80% water for a minimum of five minutes using the IST 80.6-92water repellency test method, while having a low weight water repellantmat facing 14 thereon. In one embodiment, the mat facing comprises anonwoven fiber glass mat having weight of less than 1.1 lb/100 ft² (53.7g/m²), and more preferably less than 1.0 lb/100 ft² (48.81 g/m²). In oneexemplary embodiment, the nonwoven fiber glass mat is the 27# Manniglas®1807 mat having a target weight of 0.87 lb/100 ft² (42.3 g/m² ) andmaximum weight of 0.97 lb/100 ft² (47.5 g/m²) available from LydallInc., the 23# Manniglas® 1803WHB mat having a target weight of 0.80lb/100 ft² (39.1 g/M²) and a maximum weight of 0.90 lb/100 ft² (43.9g/m²) also available from Lydall Inc. or a mat having a weighttherebetween. These exemplary nonwovens include an integral waterrepellent. In an exemplary embodiment, the nonwoven is combined, such asby saturation, with a water repellent comprising a fluorinated polymer,such as an fluorinated acrylic, fluropolymer or flurocarbon, silicone,wax, oil, wax-asphalt emulsions, acrylics, other emulsions, latexes,polyvinyl acetates, etc. The weights reflect the combined weight of thecoating and mat. In this embodiment, the desired water repellency can beachieved without the use of a water repellent added to the binder of theduct board or adhesive used to adhere the nonwoven to the duct board.

By limiting the weight of the nonwoven facing, significant cost savingscan be realized while providing a cost effective, abuse resistant waterrepellant airstream surface for the mineral fiber duct product.Presently, the 23# Manniglas® 1803WHB mat, for example, provides roughlya cost savings proportional to the percentage difference in weight overthe heavier Manniglas® 1886 black models. Additional cost savings can berealized in embodiments where no additional water repellent is added tothe binder of the duct board or adhesive used to adhere the nonwoven tothe duct board.

Samples were constructed with facing 14 made of the 23# Manniglas®1803WHB mat having target weight of 39.1 g/m², and the 27# Manniglas®1807 mat having target weight of 0.87 lb/100 ft² (42.3 g/m² ) on a fiberglass insulation board with a phenolic binder. The 1803 WHB sampleachieved an INDA 2.4 rating using the IST 80.6-92 water repellency testmethod, and the 1807 sample achieved an INDA 2.0 rating using the IST80.6-92 water repellency test method.

Although the invention has been described in terms of exemplaryembodiments, it is not limited thereto. Rather, the appended claimsshould be construed broadly, to include other variants and embodimentsof the invention, which may be made by those skilled in the art withoutdeparting from the scope and range of equivalents of the invention.

1. A duct board or duct liner product, comprising: an insulating layerformed from fibrous material bound with a resin binder; an outer facinglayer adhered to an outer surface of the insulating layer; and a waterrepellant mat facing adhered to an interior surface of the insulatinglayer opposite the outer surface to form a duct board material, the matfacing having a weight of less than 1.1 lb/100 ft² (53.6 g/m²) andhaving at least an INDA 2 water repellence rating using the IST 80.6-92water repellency test method.
 2. The duct board or duct liner of claim1, wherein the weight of said mat facing is less than about 1.0 lb/100ft² (48.73 g/m²).
 3. The duct board or duct liner of claim 1, whereinthe weight of said mat facing is between about 0.80 lb/100 ft² (39.0g/m²) and 0.97 lb/100 ft² (47.5 g/m²).
 4. The duct board or duct linerof claim 1, wherein the mat facing is formed from a non-woven fibermaterial having a water repellent material integral therein.
 5. The ductboard or duct liner of claim 4, wherein the mat facing comprisesnon-woven glass fibers bound with a resin.
 6. The duct or duct liner ofclaim 1, wherein the mat facing is adhered to a surface of saidinsulating layer by an adhesive, said adhesive and insulating layerbeing substantially free of water repellent additives or agents.
 7. Theduct board or duct liner of claim 1, wherein the mat facing comprises anon-woven fiberglass and water repellant material comprising afluorinated polymer, said mat facing having a weight between about 0.80lb/100 ft² (39.0 g/m²) and 0.97 lb/100 ft² (47.5 g/m²).
 8. The ductboard or duct liner of claim 1, wherein the resin binder in at least aportion of said insulating layer is formed from a resin in an aqueouscarrier mixed with a hydrophobic agent in emulsion form.
 9. The ductboard or duct liner of claim 8 wherein the hydrophobic agent is presentin said binder in a ratio of about 1:200 to 1:5 hydrophobic agent tobinder.
 10. The duct board or duct liner of claim 9, wherein saidhydrophobic agent is selected from the group consisting of emulsions,latexes, silicone, oil, fluorocarbon and waxes.
 11. The duct board orduct liner of claim 1, wherein: the mat is adhered to a surface of saidinsulating layer by an adhesive containing a first hydrophobic agent,and the resin binder in at least a portion of said insulating layercontains a second hydrophobic agent.
 12. The duct board or duct liner ofclaim 11, wherein the first hydrophobic agent is one of the groupconsisting of emulsions, latexes, silicone, oil, fluorocarbon and waxes.13. The duct board or duct liner of claim 11, wherein the resin binderin the portion of said insulating layer is formed from a resin in anaqueous carrier mixed with a hydrophobic agent in emulsion form.
 14. Theduct board or duct liner product according to claim 1, wherein the ductboard material is formed in a tubular shape capable of conducting air,with the mat facing on an interior thereof.
 15. A method for forming aduct board or duct liner product, comprising: (a) adhering an outerfacing layer to an outer surface of an insulating layer formed fromfibrous material bound with a resin binder; and (b) adhering a waterrepellant mat facing to an interior surface of the insulating layeropposite the outer surface to form a duct board material, the mat facinghaving a weight of less than 1.1 lb/100 ft² (53.6 g/m²) and having atleast an INDA 2 water repellence rating using the IST 80.6-92 waterrepellency test method.
 16. The method of claim 15, further comprisingforming the duct board material into a tubular shape capable ofconducting air, with the mat facing on an interior thereof.
 17. Themethod of claim 15, wherein the weight of the mat facing is less thanabout 1.0 lb/100 ft² (48.73 g/m²).
 18. The method of claim 15, whereinthe weight of the mat facing is between about 0.80 lb/100 ft² (39.0g/m²) and 0.97 lb/100 ft² (47.5 g/m²).
 19. The method of claim 18,wherein the mat facing is formed from a non-woven fiber material havinga water repellent material integral therein.
 20. The method of claim 19,wherein the mat facing comprises glass fibers bound with a resin. 21.The method of claim 20, wherein the mat facing is adhered to a surfaceof said insulating layer by an adhesive, said adhesive and insulatinglayer being substantially free of water repellent additives or agents.22. The method of claim 15, wherein the mat facing comprises a non-wovenfiberglass and water repellant material comprising a fluorinatedpolymer, said mat facing having a weight between about 0.80 lb/100 ft²(39.0 g/m²) and 0.97 lb/100 ft² (47.544.2 g/m²).
 23. A duct board orduct liner product, comprising: an insulating layer formed from fibrousmaterial bound with a resin binder; an outer facing layer adhered to anouter surface of the insulating layer; and a non-woven glass fiber matfacing adhered to an interior surface of the insulating layer oppositethe outer surface to form a duct board material, said mat facing havinga water repellent material integral therein, the mat facing having aweight of between about 0.80 lb/100 ft² (39.0 g/m²) and 0.97 lb/100 ft²(47.5 g/m²) and having at least an INDA 2 water repellence rating usingthe IST 80.6-92 water repellency test method, wherein the mat is adheredto a surface of said insulating layer by an adhesive, said adhesive andinsulating layer being substantially free of water repellent additivesor agents.
 24. The duct board or duct liner product according to claim23, wherein the duct board material is formed in a tubular shape capableof conducting air, with the mat facing on an interior thereof.
 25. Theduct board or duct liner product according to claim 23, wherein saidwater repellent material comprises a fluorinated polymer.